Obama spoke by phone late Thursday with Hailemariam Desalegn, who was named acting prime minister this week after longtime leader Meles Zenawi died at the age of 57.

The White House says Obama pledged continued U.S. "partnership" with Ethiopia, which under Meles has been a strong U.S. ally in the war against radical groups such as Somalia's al-Shabab.

Ethiopians are still awaiting word on when Mr. Hailemariam will be formally sworn in. Parliament was set to install him on Thursday but the session was canceled.

A government spokesman said Ethiopians wanted more time to mourn Meles, who led Ethiopia for 21 years. The late prime minister's funeral is scheduled for September 2.

On Tuesday, Communications Minister Bereket Simon rejected concerns about a power vacuum resulting from Meles' death. He said the country's leadership is united and the government is as "strong as ever."